6 - amidinothio - 5,7 - dihydroxy - s - triazolo(2,3-a) pyrimidino compounds as stabilizers for silver halide emulsion

ABSTRACT

A LIGHT-SENSITIVE SILVER HALIDE PHOTOGRAPHIC ELEMENT BEARS ON A SUPPORT A PHOTO-SENSITIVE LAYER CONTAINING A 6AMIDINOTHIO-5,7-DIHYDROXY-S-TRIAZOLO(2,3-A)PYRIMIDINE COMPOUND OF THE FORMULA:   2-R,5,7-DI(HO-),6-(H2N-C(=NH)-S-)-S-TRIAZOLO(4,3-B)-   PYRIDAZINE   WHEREIN R MEANS HYDROGEN OR A LOWER ALKYL GROUP. THE COMPOUNDS ACTS AS A STABILIZER TO PROLONG THE LIFE OF THE PHOTOGRAPHIC ELEMENT.

United States Patent 3,565,631 6 AMIDINOTHIO 5,7 DIHYDROXY s TRIA- ZOL0[2,3-a]PYRIMIDINO COMPOUNDS AS STA- BILIZERS FOR SILVER HALIDE EMULSION Masanobu Oguchi and Yoshimi Kuwabara, Tokyo, and

Katsuo Mogaki, Odawara-shi, Japan, assignors to Konishiroku Photo Industry Co., Ltd., Tokyo, Japan No Drawing. Filed July 7, 1967, Ser. No. 651,664 Int. Cl. G03c 1/34 US. Cl. 96-109 5 Claims ABSTRACT OF THE DISCLOSURE A light-sensitive silver halide photographic element bears on a support a photo-sensitive layer containing a 6 amidinothio 5,7 dihydroxy-s-triazolo[2,3-a]pyrimidine compound of the formula:

wherein R means hydrogen or a lower alkyl group. The compounds acts as a stabilizer to prolong the life of the photographic element.

This invention relates to photographic composition, and more particularly, it concerns with a light-sensitive silver halide photographic element, e.g. photographic film, paper or plate, bearing on a support a photo-sensitive layer containing a certain 6-amidinothio-5,7-dihydroXy-s-triozolo-- [2,3-a1pyrimidine compound.

In the art it is well known that photographic compositions, when stored for a long period after their preparation, suffer from decrease in speed and formation of undesired fog. In order to prevent these adverse effects, a variety of stabilizers also have been proposed. Incorporation of the known stabilizers, however, is disadvantageous because it usually causes decrease in speed, and the demand in the art has been directed to develop a stabilizer which will permit to prevent fog without any adverse influence on photographic sensitivity.

It is accordingly one object of the present invention to provide a light-sensitive silver halide photographic composition which can resist to any undesired effect caused by storage over a long period of time. Other objects, features, capabilities and advantages which are comprehended by the invention will be apparent from the specification and claims which follow.

The above-mentioned and other objects can be attained by incorporating a certain pyrimidine compound as a stabilizer into a light-sensitive silver halide photographic composition.

We have now found that if a compound of the general formula,

s N N Patented Feb. 23, 1971 layers of a photographic element, such layers including emulsion layers, sub-layers, inter layers, protective layers and backing layers. Another advantage of the present invention is that where the said compound is added to a photographic emulsion during its ripening or digestion, it is possible to prevent fog formation and consequently to facilitate an increase of speed due to the ripening or digestion. Further advantage of the present invention is that a compound of the above general formula is effective in a very small amount, e.g. about one-thirtieth of the amount required for 5 methyl 7 hydroxy-s-triazolo [2,3-a1-pyrimidine which is known stabilizer. Still further, a compound of the present invention shows the less desensitizing effect under high temperature and high humidity conditions in comparison with the said known stabilizer.

Typical compounds which are included within the scope of the above-indicated general formula can be listed below:

In corporation of the pyrimidine compound into a layer or layers of the photographic element of the present invention can be made in the manner heretofore known per se in the art. For example, where the pyrimidine compound is to be present in an emulsion layer of the said clement, it is possible to add the said compound into the emulsion at any time just before, during or after the second ripening of the said emulsion. Addition of the pyrimidine compound at the stage after the second ripening of the emulsion is most preferred. Alternatively, it may be added to a starting material for preparation of the emulsion, for example, gelatine. The amount of the pyrimidine compound to be added will vary depending on the type of emulsions, the degree of stabilization desired and the type of a layer to which the stabilizer is added, but it usually is within the range of from 1 mg. to 200 mg. per liter of the silver halide emulsion. It is desirable to add the compound in solution dissolved in a suitable solvent, e.g. water, dilute hydrochloric acid, methanol, ethanol, etc.

Use of the pyrimidine compound as a stabilizer does not adversely influence on sensitization of a photographic silver halide emulsion concerned. Thus, the photographic emulsion containing the pyrimidine compound can be sensitized by way of gold, sulfuror other chemical sensitization or optical sensitization. The pyrimidine compound may be used in combination with any other known stabilizer, e.g. a tetrazaindene derivative. Furthermore, the same compound sometimes can provide desirable effeet to facilitate an increase of speed because it will prevent increased fog which frequently occurs accompanying to the sensitization. It is, of course, true that decrease of speed and increase of fog during storage of the emulsion also can be prevented by use of the pyrimidine compound.

Still another advantage of the present invention is that fog and desensitization both which frequently occur duracid and then fixed, washed and dried. The results are set forth in Table I.

ing the storage of a color photographic material containing the large amount of color formers in the emulsion can be effectively prevented by use of the stabilizer according to the present invention.

The emulsion to which the stabilizer has been added can be applied to a suitable support in the manner heretofore known per se in the art, e.g. coating or pouring. Suitable supports include films, papers and glass plates. Particularly suitable are films of the types, such as cellulose esters, e.g. cellulose triacetate; polyesters obtained by the polycondensation of phthalic, isophthalic or terephthalic acid with a dihydric alcohol, e.g. polyethylene alate, etc.; and polycarbonates including those obtained by the polycondensation of Bis-phenol A with carbonic acid.

The following examples describe certain ways in which the principle of the invention has been applied, but are not to be construed as limiting its scope.

In this test, photographic sensitivity which usually is an inverse number of the amount of light exposure to give 15 an optical density of 0.1 above fog density, is expressed The photographic emulsion used in Example 1 is sub ected to second ripening and then sensitized by the addition of dodecylethyleneoxide lauryl ether in the amount terephthalate, poly[cyclohexane-l,4-dimethylol1terephth- 25 of 1 mg per hter of the emulslon' Thereafter the emulsion is divided to three portions, one of which is used for preparation of control film and the other two used by addition of various pyrimidine compounds indicated below. Each portions are coated to supports. The films thus prepared are subjected to the same sensitometric tests as described in Example 1. The results are set forth in Table II.

TABLE II Iucubated at Incubated at 55 C. 55 C. and 80% for 3 days after RH for 3 days Fresh preparatlon after preparation Amourit R 1 use e ative Relative Relative Compound 1ug./l. speed Fog speed Fog speed Fog Control 100 0.05 40 0.95 0 1.90 CompoundI 4 100 0.05 130 0.10 85 0.15 Compound III- 4: 100 0. 05 120 0. 80 0.

EXAMPLE 1 A silver iodo-bromide emulsion useful for high speed EXAMPLE 3 negatives and containing 3% by mole of silver iodide is prepared according to neutral process. This emulsion is subjected to second ripening at a temperature of C. for minutes. After the said ripening, the emulsion is divided to three portions, one of which is used for preparation of control film and the other two used in combination with various pyrimidine compounds indicated in Table 1. Each portions are prepared to form films which in turn are stored under the conditions indicated in Table 1. Samples of these film coatings were then exposed in an intensity-scale type sensitometer and developed for five minutes in a developer of the following formulation:

Grams Metol (p-methylaminophenol sulfate) 2.0 Sodium sulfite (anhydrous) 50.0 Hydroquinon 4.0 Sodium carbonate (monohydrate) 7.0 Potassium bromide 0.75

Water to make 1.0 liter.

The developed samples were stopped with dilute acetic The silver iodobromide emulsion used in Example 1 50 is added with sodium thiosulfate, as sulfur sensitizer, in

60 and min. after initiation of the second ripening, in-

dividual samples are taken from both of the emulsions and coated on supports to obtain films, which are then subjected to the sensitometric test described in Example 1. The results are set forth in Table III, wherein a relative speed is an index value when the specific value of the control film obtained after 60 minutes-ripening is rated as 100.

From the above table it is clear that the emulsion to which a stabilizer of the present invention is added is favored with the smooth increase of photosensitivity, with the less occurrence of fog, in response to the progress of second ripening, while it has a relative speed somewhat lower than that of the control emulsion at the earlier stage of said ripening.

EXAMPLE 4 The silver iodobromide emulsion used in Example 1 is subjected to second ripening at 60 C. for 75 minutes and then added with a color former solution containing 1- (4-phenoxy-3'-sulfophenyl)-3-heptadecyl-5 pyrazolone. The resulting mixture is coated on a film base. On the light-sensitive surface of the thus obtained film, a 3% gelatine solution which is not added or added with the pyrimidine compound I is coated as a protective layer. Some of the resulting films are stored in the same manner as in Example 1. The stored and unstored films are treated by development with a color developer containing diethyl-p-phenylenediamine, followed by bleaching, water-washing, fixing and then water-Washing. The sensitometric test results obtained are set forth in Table IV, which indicates that the incorporation of the pyrimidine compound in a protective layer also is efiective for prevention of fogging.

TABLE IV What we claim is:

1. A light-sensitive, photographic silver halide element, at least one of the gelatin-containing layers of which contains silver halide and a stabilizing amount of a compound of the formula wherein R is hydrogen or a lower alkyl.

2. A light-sensitive, photographic element containing a silver halide emulsion as claimed in claim 1; further comprising a member selected from the group consisting of sulfur-, goldand reduction sensitizers.

3. A light-sensitive, photographic element containing a silver halide emulsion as claimed in claim 1; further comprising an optical sensitizer.

4. A light-sensitive, photographic element containing a silver halide emulsion as claimed in claim 1; further comprising a color coupler.

5. A light-sensitive, photographic element containing a silver halide emulsion as claimed in claim 1; further comprising a tetraz aindene derivative as stabilizer.

Ineubated at 55 C. for 3 days after Fresh preparation Incubated at 55 C. and 80% RH for 3 days after preparation Amount used,

mgJl.

Relative speed Fog Relative Compound speed Fog Relative speed Fog Control Compound I 10 References Cited UNITED STATES PATENTS 9/1961 Fry 96-109 3,220,839 11/1965 Herz et al. 96-109X 

